1. Field of the Invention
This invention relates to amide compositions, particularly long chain amide compositions, useful for softening textile materials, including fabrics, yarns and fibers. In particular, the invention relates to the composition of alkyl (about 8 to about 22 carbon atoms) amides and alkylpolyglycosides, concentrates of which are dilutable to aqueous solutions employed for softening textile materials, particularly fabrics, which solutions are viscosity-stable over long periods and which provide improved softening properties.
2. Discussion of Related Background Art
A most important class of textile finishing agents is the softeners, whose function is to modify the surface feel, called "hand". The fabric is made soft or pleasant to the touch and also possesses aesthetic draping qualities. Softeners may be used as finishes in themselves or together with other finishing agents, to overcome the inherent harshening characteristic of the other finishes.
A "pure" finish refers to application of the softener, by itself, to the textile material, generally a fabric, but may include the fiber of a yarn itself, to be later formed into fabric. In a pure finish no other chemical is generally present in the bath except, possibly a wetting agent if the fabric is dry. The total effect on the fabric, other than softening, may be improved sewability, improved absorbency or a decrease in the fiber to fiber or fiber to metal friction.
As a finish bath component, the softener performs several functions. In resin baths applied to materials, such as polyester-cotton knits or woven goods, it may act to plasticize the resin and reduce the harshness of the hand. It frequently will add lubricity to the fiber surface and improve sewability by minimizing heat buildup of the sewing needle, thereby eliminating needle cutting. The improved lubricity will also help minimize abrasion and improve tear strength.
Since softeners are usually the last chemical applied to yarn or fabric, commercial softeners must meet certain requirements. Softeners must be
(a) non-yellowing
(b) odor-free
(c) compatible with other finish bath components
(d) have no negative effect on dye shade
(e) non-volatile and non-smoking
(f) non-scorching, and
(g) stable.
A wide variety of chemical structures have been used in the past to serve as softening agents, almost all of them being based on fatty acids having chain lengths of about 8 to 22 carbon atoms. Among the preferred softeners are the fatty acid amides. Such amide softening agents are supplied commercially in concentrate form for dilution by the customer for formulation with other finish bath components. While the amide softening agents provide good softening properties and generally meet the requirements for softening agents, it has generally been necessary to add emulsifiers or diluents such as glycols and ethoxylated phenols, thereto to provide storage stable compositions, either as concentrates, or in a diluted form for use. In storage for any long period of time, amide softeners tend to gel, or increase or vary in viscosity when stored, or in use, over an extended period of time. Changes in viscosity of the finish bath can effect the deposition of the softeners to the fabric, resulting in uneven distribution of the softener to the fabric. In the past, emulsifiers and diluents employed, while lowering viscosity somewhat of the dilute solution to be applied to the fabric, tended to increase in viscosity, or vary in viscosity, over periods of time in which they were to be used or stored for use. For ease in application, as well as thorough application to the fabric, the viscosity should be relatively low and uniform, so that the solution can be easily applied with uniform application to the fabric without undue or non-uniform build up.
While not dealing directly with the softening of textiles, U.S. Pat. No. 4,795,675 relates to a treatment of fabrics to impart improved heat transfer printability thereto, employing alkyl glucosides in which the alkyl groups contain from 2-8, preferably 2-6 carbon atoms, with butyl glucoside being preferred. Other auxiliary treating agents may be employed along with glucoside, including up to about 5 weight percent of a conventional fabric softening ingredient, e.g. fatty acid amide fabric softener ingredients, (column 5, lines 52-55). In Example 2 of the patent an aqueous solution containing 7.5% of a monoglucoside, methyl glucoside, which also contains 3% of a fatty acid amide softener, is employed.